﻿// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Collections;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Windows.Forms.Design.Behavior;

namespace System.Windows.Forms.Design;

/// <summary>
///  Provides a designer that can design components that extend ComboBox.
/// </summary>
internal class ComboBoxDesigner : ControlDesigner
{
    private EventHandler? _propChanged; // Delegate used to dirty the selectionUIItem when needed.

    private DesignerActionListCollection? _actionLists;

    public override ComboBox Control => (ComboBox)Component;

    /// <summary>
    ///  Adds a baseline SnapLine to the list of SnapLines related
    ///  to this control.
    /// </summary>
    public override IList SnapLines
    {
        get
        {
            IList<SnapLine> snapLines = SnapLinesInternal;

            // a single text-baseline for the label (and linklabel) control
            int baseline = DesignerUtils.GetTextBaseline(Control, Drawing.ContentAlignment.TopLeft);
            baseline += 3;
            snapLines.Add(new SnapLine(SnapLineType.Baseline, baseline, SnapLinePriority.Medium));

            return snapLines.Unwrap();
        }
    }

    /// <summary>
    ///  Disposes of this object.
    /// </summary>
    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            // Hook up the property change notification so that we can dirty the SelectionUIItem when needed.
            if (HasComponent && _propChanged is not null)
            {
                Control.StyleChanged -= _propChanged;
            }
        }

        base.Dispose(disposing);
    }

    /// <summary>
    ///  Called by the host when we're first initialized.
    /// </summary>
    public override void Initialize(IComponent component)
    {
        base.Initialize(component);

        AutoResizeHandles = true;

        // Hook up the property change notification so that we can dirty the SelectionUIItem when needed.
        _propChanged = new EventHandler(OnControlPropertyChanged);
        Control.StyleChanged += _propChanged;
    }

    /// <summary>
    ///  We override this so we can clear the text field set by controldesigner.
    /// </summary>
    public override void InitializeNewComponent(IDictionary? defaultValues)
    {
        base.InitializeNewComponent(defaultValues);

        // in Whidbey, formattingEnabled is TRUE
        Control.FormattingEnabled = true;

        PropertyDescriptor? textProp = TypeDescriptor.GetProperties(Component)["Text"];
        if (textProp is not null && textProp.PropertyType == typeof(string) && !textProp.IsReadOnly && textProp.IsBrowsable)
        {
            textProp.SetValue(Component, string.Empty);
        }
    }

    /// <summary>
    ///  For controls, we sync their property changed event so our component can track their location.
    /// </summary>
    private void OnControlPropertyChanged(object? sender, EventArgs e)
    {
        BehaviorService?.SyncSelection();
    }

    /// <summary>
    ///  Retrieves a set of rules concerning the movement capabilities of a component.
    ///  This should be one or more flags from the SelectionRules class. If no designer
    ///  provides rules for a component, the component will not get any UI services.
    /// </summary>
    public override SelectionRules SelectionRules
    {
        get
        {
            SelectionRules rules = base.SelectionRules;
            ComboBoxStyle style = ComboBoxStyle.Simple;
            PropertyDescriptorCollection props = TypeDescriptor.GetProperties(Component);
            if (props.TryGetPropertyDescriptorValue("DropDownStyle", Component, ref style))
            {
                // Height is not user-changeable for these styles
                if (style is ComboBoxStyle.DropDown or ComboBoxStyle.DropDownList)
                {
                    rules &= ~(SelectionRules.TopSizeable | SelectionRules.BottomSizeable);
                }
            }

            return rules;
        }
    }

    public override DesignerActionListCollection ActionLists
    {
        get
        {
            if (_actionLists is null)
            {
                _actionLists = new DesignerActionListCollection();

                // TODO: investigate necessity and possibility of porting databinding infra
#if DESIGNER_DATABINDING
                // Requires:
                // - System.Windows.Forms.Design.DataMemberFieldEditor
                // - System.Windows.Forms.Design.DesignBindingConverter
                // - System.Windows.Forms.Design.DesignBindingEditor
                //
                _actionLists.Add(new ListControlBoundActionList(this));
#else
                _actionLists.Add(new ListControlUnboundActionList(this));
#endif
            }

            return _actionLists;
        }
    }
}
